Pig Health - Piglet Mortality in the Outdoor Herd

Because the nature of outdoor pig production does not allow
close supervision of young piglets on the sow, in the way that can
be done in farrowing crates indoors, it is often more difficult to
identify the most significant causes of death in the newborn
pig.

Moreover, it is even difficult to know exactly the levels of
death, the only figure available that is verifiable is the numbers
weaned. Stillborn pigs and those dying in the first 24hrs of
life may be eaten by the sow or buried within straw bedding meaning
their existence may never be known to the stockman. An outdoor herd
with low weaned/litter productivity presents the challenge to
ascertain whether it is a breeding problem (producing low litter
size) a farrowing related problem producing unfound stillborn pigs
or a lactation husbandry problem causing high mortality.
Consolidated herd records suggest that UK outdoor herds produce
both less pigs born alive and higher piglet mortalities limiting
overall weaning numbers compared to indoor herds.

Stillborn pigs and those dying in the first 24hrs of life may be
eaten by the sow or buried within straw bedding meaning their
existence may never be known to the stockman. An outdoor herd with
low weaned/litter productivity presents the challenge to ascertain
whether it is a breeding problem (producing low litter size) a
farrowing related problem producing unfound stillborn pigs or a
lactation husbandry problem causing high mortality. Consolidated
herd records suggest that UK outdoor herds produce both less pigs
born alive and higher piglet mortalities limiting overall weaning
numbers compared to indoor herds.

However, certain principles can be applied that provide the
basis for reducing losses. When born, there is a dramatic
drop in the temperature to which the piglet is exposed.
Moreover, as it dries off, latent heat of vaporisation is extracted
from the piglet with the result that body temperature falls.
This hypothermia can only be offset:-

a) by reducing the heat loss

b) by the piglet burning energy to maintain body temperature

Heat Loss

In the absence of active management techniques such as drying
and use of infra red lamps such as may be used in the tpical indoor
farrowing facility, the outdoor born pig can only rely on warmth
from mother and the warming and drying effects of the bed.
Huddling together will also preserve heat.

Features of the bed which will affect heat loss include:-

1) Quantity of straw - there is a very fine art to bedding
outdoor arcs. Too little and the piglets chill; too much and
small piglets become entangled making them vulnerable to crushing
by the sow.

2) Quality of the straw - short chopped barley straw that is
clean, dry and fresh provides the best medium.

3) Dampness - the wetter the bed, the greater the heat
loss. At wet times of the year, there is a balance to be
found between providing a new bedded area that is clean on wet
ground. Normally arcs should be moved to a new site for each
farrowing with old beds either lifted and removed or burnt in
situ. Some producers, in wet conditions, may prefer to add
new bedding on top of the old but this should only be limited to
one off situations. Lying boards may be used in extreme
circumstances.

4) Frequency of bedding - allowing the sow a week to settle the
bed prior to farrowing should be followed up with daily addition of
clean straw; bare in mind that the sow may eat some of it.

5) Draughts - orientate arcs away from prevailing winds and
always ensure there are no gaps around the base. Either pack
straw at the base of the arc from the inside or earth up around the
outside. Doors closed during farrowing may also help as may the
tight fitting of the fender.

Conversely it should be borne in mind that in very high ambient
temperatures a deep compacted straw bed will limit the sow's
ability to dissipate heat leading to overheating, likely to raise
stillbirth levels, desertion from the arc rendering new born
piglets more vulnerable or disturbance of the bedding. In extremely
warm conditions reduction of bedding material maybe appropriate but
a fine balance is still required between the needs of the sow and
the needs of the piglets at birth.

Energy Supply

In exactly the same way as would apply
indoors, increasing sow feed levels between weeks 13 and 15
gestation will boost energy reserves in newborn piglets, giving
them a greater change to maintain body heat. An early suck of
adequate amounts of colostrum is essential but the ability of the
stockmen to influence this by assisted suckling, split suckling and
fostering is more limited than in the indoor farrowing facility.
Discuss with your veterinary surgeon or nutritional advisor the
most appropriate strategy for your herd.

Chilling is the underlying feature of a large number of piglet
deaths, both indoors and out. Not only can pigs die directly
due to hypothermia, but chilled pigs tend to be slow moving, making
them vulnerable to crushing and will not receive sufficient
colostrum, making them vulnerable to infection in the first few
weeks of life.

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